Tunneling cutter gage ring replacement

ABSTRACT

A rotary cutter for tunneling machines comprising one of a series of gage cutters about the periphery of a face plate, the outer or gage end of the gage cutters being subject to rapid deterioration resulting in wearing away of the metal of the body of the cutter and displacement of the hardened metal inserts around the gage end, a gage ring about the gage end being produced by cutting inwardly beneath the gage row and possibly one or more additional rows of hardened inserts, and then cutting down from a valley between rows of hardened inserts to the first described separation to provide a removable and replaceable gage ring portion on the cutter containing peripheral rows of hardened metal inserts in the same manner as the damaged gage ring portion being replaced.

nlted States Patent [151 3,666,629

Dixon 5] 30, R972 54] TUNNELING CUTTER GAGE RING 3,593,812 7 1971Peterson ..175/374 x REPLACEMENT Primary ExaminerDavid H. Brown [72]Inventor. Robert L. Dixon, Whittier, Calif. Atmmey Anan D M ock ab 6 e[73] Assignee: Smith International, Inc., Newport Beach,

Calif. [5 7] ABSTRACT [22] Filed: Oct. 23, 1970 A rotary cutter fortunneling machines comprising one of a series of gage cutters about theperiphery of a face plate, the [21] Appl' 83508 outer or gage end of thegage cutters being subject to rapid deterioration resulting in wearingaway of the metal of the [52] US. Cl. ..l75/374, 76/ 108 A body of thecutter and displacement of the hardened metal in- J32? 9/12, 13/01 sertsaround the gage end, a gage ring about the gage end [58] Field of Search1 75/342, 353, 374, 375, 383, being produced by cutting inwardly beneaththe gage row and 175/382 361-364; 76/108 A? 79/401 526 possibly one ormore additional rows of hardened inserts, and then cutting down from avalley between rows of hardened in- [56] References cued serts to thefirst described separation to provide a removable UNITED STATES PATENTSand replaceable gage ring portion on the cutter containing peripheralrows of hardened metal inserts in the same manner 2,704,204 3/1955KOOHIZ 175/374 X as the damaged gage ring portion being replaced.3,326,307 6/1967 Rudy ....l75/374 3,216,513 11/1965 Robbins et al...175/374 X 6 Claims, 6 Drawing Figures Patented May 30, 1972 2Sheets-Sheet 'IY INVENTOR 05667 4. D/XOA/ Patented May 30, 1972 2Sheets-Sheet 2 INVENTOR 05657 D/XG/V ATTOE/WS TUNNELING CUTTER GAGE RINGREPLACEMENT This invention relates to a method of providing a rotarycutter for tunneling machines and the like wherein the cutter body,generallyfrusto-conical, is provided with spaced circumferential rows ofhardened metal inserts, preferably of tungsten carbide. The invention isalso directed to a cutter resulting from the replacement method. Thereplaceable gage ring portion of the cutter with its hardened insertsand the remainder of the cutter body with its inserts can be initiallyconstructed with a separate gage ring or, according to the method, aconventional cutter can be so operated upon that a removable gage ringportion is produced and a replacement gage ring portion provided.

Cutters of this type are disclosed in my copending application forpatent, Ser. No. 33,819, filed May 1, 1970 and entitled Rock BoringCutter.

When boring tunnels with apparatus of this type, a vertically disposedrotary face plate provided with rotary cutters on its advance face,works against the rock formation. The face plate has an outer diameterabout which is located certain of the rotary cutters which are termedgage cutters, since they detennine the gage of the out being made. Thegage cutters, conventionally frusto-conical in shape, have their largerends at the gage or peripheral of the tool, and their outer end facesand outer skirt portions with rows of hardened metal inserts thereaboutare subject to much more destructive action than other portions of thegage cutters or other cutters located inwardly from the gage line. Notonly do the gage ends of the gage cutters encounter uncut rock in frontof and beside them, but they are also subjected to the abrasive actionof broken pieces of formation working between the sides of the uncutformation and the outer or gage ends of the gage cutters. These portionsof the gage cutters wear away relatively rapidly and soon the hardenedmetal inserts in the gage row of inserts are left without adequatesupport in the metal of the cutter body and they become displaced andthe cutters will no longer operate efficiently.

ln view of the fact that the rotary cutters discussed herein areconventionally formed in one piece to maintain them as strong aspossible under the considerable pounding and abrasion to which they aresubjected, because these cutters are studded rather profusely withhardened metal inserts and because no feasible manner of rehabilitationof the cutters has heretofore been conceived, they have been discardedwhen the gage ends of the cutters become worn and the gage row of metalinserts displaced, at least in part.

Attempts have been made to prolong cutter life by hard facing the gageends of the cutter bodies with a layer of hard weld material but thisdoes not sufficiently prolong cutter life to make it practical. It hasalso been impractical from an economic standpoint to try to build up theworn away gage end of the cutter body. The result is that in practice,until the time of the present invention, gage cutters which are worn asstated above, have been discarded as no longer fit for use. However,with the practice of my invention, it has been found quite feasible notonly to reclaim worn gage cutters with displaced hardened inserts in thegage and adjacent rows, but it has also been found feasible to provide agage cutter construction which initially is made with a separate gagering portion which when worn to the point where the gage row of hardenedinserts suffers partial or complete loss of inserts, the gage ringportion can be replaced. In either case, the effective life of the gagecutters of this type has been increased several fold because of theability to provide new rows of gage inserts and replaceable gage ringbody portions.

The above and other advantages become more apparent from the followingdescription in connection with the accompanying drawings.

FIG. 1 is a side elevational view of a gage cutter and its mounting witha peripheral portion of a face plate in section;

FIG. 2 is an enlarged vertical longitudinal sectional view through acutter embodying a feature of the invention and showing the manner inwhich the cutter is rotatably mounted;

FIG. 3 is a fragmentary sectional view through the gage of end of acutter showing a form of replaceable gage ring;

FIG. 4 is an end elevation of the gage end of a cutter;

FIG. 5 is an enlarged fragmentary sectional view similar to FIG. 3 andshowing some of the gage row of hardened inserts;

FIG. 6 is an enlarged fragmentary sectional view through a portion ofthe gage end of a gage cutter with another form of separate gage ringand its inserts.

There is illustrated in FIG. 1 a portion of a rotary face plate 8, suchas illustrated in the above identified copending application. This platehas an outer peripheral edge portion 10 which carries a bracket 12secured by bolts 14. The bracket 12 has an upstanding shirttail portion16 from which projects a bearing journal 18, shown in FIG. 2. The outerend of the journal 18 is supported by a bracket 19 which may be securedto the face plate 8 by welding. Mounted on the journal are bearingassemblies generally designated at 20 and 22, which support afrusto-conical rotary gage cutter 24 about the side wall of which arerows of hardened metal inserts 26, the row at the left or larger end ofthe cutter comprising a row of gage inserts 28. The next adjacent row28A can also be considered a gage row although strictly speaking theouten'nost row is so considered.

It will be seen in FIG. 1 that the left or gage end of the cutter 24 isprovided with a beveled portion 30 which is more or less aligned withthe outer surface 16A of the shirttail. Cutter surface 31 whichsurrounds the hardened metal inserts, outer surface 30 and the shirttailare subjected to a great deal of abrasion from parts of the formationwhich have been cut away and which tend to accumulate about the gageportion of the face plate 8 due to the difficulty in removing thecutaway formation quickly enough to prevent such accumulation andabrasion. This accumulation is one of the functional difficultiesencountered in machinery of this type. Actually however, much of theextreme wear is taken by the beveled surface 30 around the gage end ofthe cutter. The metal of the cutter body wears away fairly rapidly sothat there is insufficient material to hold the inserted hardenedelements 28, and sometimes the next row 28A, with the result that whenthe inserts loosen and become lost, the entire gage comer of the cutter24 fails to perform its proper cutting action and the cutter heretoforehas been discarded.

I have found that cutter life can be prolonged to some extent by theapplication of a hard surface weld to the surfaces 30 and 31 of thecutter but the time and expense involved, compared to the relativelyshort lengthening of cutter life, is not a satisfactory answer. Becauseof the presence of the hardened metal inserts in the side wall of thecutter, it has heretofore been considered impractical to remove theinserts and machine the cutter preparatory to replacing portionsthereof, and because of the shocks and heavy loads to which the cuttersare subjected, it has always been considered impractical to try toproduce anything .other than a heavy onepiece cutter body.

I then found that worn cutters with missing inserts in their gage rowscan be rehabilitated by cutting inwardly along a surface of revolution32 to a point inwardly past two or three circumferential rows ofhardened inserts. I then cut downwardly along a plane 34 to intersectwith the face 32, the cut 34 preferably being made inwardly from avalley 36 located between adjacent rows of hardened inserts. The valleysare provided on the cutters to facilitate chip clearance.

Then I provide a replacement gage ring portion 38 which is pressed onthe surface of revolution 32 until it abuts tightly against the surface34. Then the replacement gage ring portion can be secured by welds at 40and 42. The replacement gage ring portion 30 of course is provided withthe proper replacement rows of hardened inserts, and when the ring hasbeen forced into position and welded, the cutter is in condition for ause life equal to its original use life until gage ring portionreplacement is again required. The remainder of the cutter body willstand up considerably longer than the gage ring portion so that theeffective life of the cutter is increased at least several times.

With the gage ring portion 38 pressed onto the surface of revolution 32and welded in position, the cutter assembly is substantially as solid asif the cutter body were in one piece.

In FIGS. 3 and 5, there is shown an embodiment wherein a cutter body 44is provided similar to the cutter body 24 of the first embodiment.However, in this form there is a gage ring body portion 46 which'can bepressed into position and then secured by bolts 48 instead of by weldsso that replacement is facilitated when the gage ring portion becomesworn. To relieve the bolts 48 from the shear forces tending to rotatethe gage ring portion 46, I provide dowels 50 between the bolts 48 asindicated in FIG. 4. In FIGS. 3 through the gage row of inserts 52 isshown, and in FIG. 5 a portion of the next adjacent row of inserts 54 isillustrated.

In FIG. 6 there is shown a cutter body portion 56 and a replaceable gagering portion 58 which may be secured by welds 60. As shown, the ringportion is formed at its outer comer on more of a radius than the ringportions 46 and 38. Also, ring portion 58 is provided with hardenedinsert sockets 62 which are closer together than in the otherembodiments so that a more complete hardened insert armon'ng of theradiused surface of the gage ring 58 is provided.

From the foregoing it will be seen that I have provided a method andproduct wherein the life of gage cutters for tunneling machines can begreatly increased by providing a specific type of replaceable gage ringportion of the cutter body, which portion carries one or more rows ofnew and tightly embedded hardened metal inserts.

It will of course be understood that various changes can be made in theform, detail, arrangement and proportion of the parts, and the specificsteps of the method, without departing from the spirit of the invention.

Iclaim:

l. A method of replacing the gage ring portion of a rotary tunnelingcutter having a metal body with an axis of rotation and having hardenedmetal inserts embedded therein in rows thereabout, beginning with a gagerow at the gage end of said body, said rotary body, at its gage end,having an end face, wherein the method includes: providing a first areaof separation constituting a surface of revolution located radiallyoutwardly from said axis of revolution and radially inwardly from theinner ends of said hardened metal inserts, said area of separationextending axially inwardly from said end face a distance beyond at leastthe gage row of inserts, said area of separation terminating at a planetransverse to said axis of rotation and located between two of said rowsof inserts, providing a second area of separation about said body fromthe circumference of the body inwardly of said transverse plane andintersecting said first area of separation, the two areas of separationdefining a removable gage ring portion, and replacing a worn gage ringportion having displaced hardened metal inserts with an unwom gage ringportion having a complement of hardened metal inserts.

2. The method in claim 1, and providing welds along the exposed adjacentsurfaces of said rotary body and said replaced gage ring portion.

3. The method of claim 1, and the replacing of an unwom gage ringportion being accomplished by pressing the ring portion on the rotarybody and then mechanically securing the ring to the body.

4. The method in claim 1, and the replacing of an unworn gage ringportion being accomplished by pressing the ring on the rotary body, andlocking the ring against rotation about the body with dowels.

5. The method in claim 1, and the replacing of an unwom gage ringportion being accomplished by pressing the ring on the body, bolting thepressed ring to the body, and locking the ring against rotation aboutthe body with dowels.

6. A rotary gage cutter for tunneling machines and the like for useabout the edge or gage surface of a rotary face plate, wherein theimprovement comprises: a rotary cutter body having an axis of rotationand having a side wall with a plurality of spaced rows of hardened metalinserts therein, said body having valleys circumferentially about itsside wall between rows of inserts, the cutter body having a gage endadapted to lie at the gage edge portion of a rotary face plate, saidgage end being of reduced diameter axially inwardly from said end andterminating at a plane transverse to said axis of rotation andcoinciding with a valley portion between adjacent rows of inserts, saidbody enlarging approximately to its side wall diameter along said plane,to provide, with said reduced diameter, a circumferential rabbet aboutsaid body, a gage ring having about its circumference at least one rowof hardened meta inserts, and means securing said gage ring on saidreduced diameter of said body and in said circumferential rabbet.

* k i i

1. A method of replacing the gage ring portion of a rotary tunnelingcutter having a metal body with an axis of rotation and having hardenedmetal inserts embedded therein in rows thereabout, beginning with a gagerow at the gage end of said body, said rotary body, at its gage end,having an end face, wherein the method includes: providing a first areaof separation constituting a surface of revolution located radiallyoutwardly from said axis of revolution and radially inwardly from theinner ends of said hardened metal inserts, said area of separationextending axially inwardly from said end face a distance beyond at leastthe gage row of inserts, said area of separation terminating at a planetransverse to said axis of rotation and located between two of said rowsof inserts, providing a second area of separation about said body fromthe circumference of the body inwardly of said transverse plane andintersecting said first area of separation, the two areas of separationdefining a removable gage ring portion, and replacing a worn gage ringportion having displaced hardened metal inserts with an unworn gage ringportion having a complement of hardened metal inserts.
 2. The method inclaim 1, and providing welds along the exposed adjacent surfaces of saidrotary body and said replaced gage ring portion.
 3. The method of claim1, and the replacing of an unworn gage ring portion being accomplishedby pressing the ring portion on the rotary body and then mechanicallysecuring the ring to the body.
 4. The method in claim 1, and thereplacing of an unworn gage ring portion being accomplished by pressingthe ring on the rotary body, and locking the ring against rotation aboutthe body with dowels.
 5. The method in claim 1, and the replacing of anunworn gage ring portion being accomplished by pressing the ring on thebody, bolting the pressed ring to the body, and locking the ring againstrotation about the body with dowels.
 6. A rotary gage cutter fortunneling machines and the like for use about the edge or gage surfaceof a rotary face plate, wherein the improvement comprises: a rotarycutter body having an axis of rotation and having a side wall with aplurality of spaced rows of hardened metal inserts therein, said bodyhaving valleys circumferentially about its side wall between rows ofinserts, the cutter body having a gage end adapted to lie at the gageedge portion of a rotary face plate, said gage end being of reduceddiameter axially inwardly from said end and terminating at a planetransverse to said axis of rotation and coinciding with a valley portionbetween adjacent rows of inserts, said body enlarging approximately toits side wall diameter along said plane, to provide, with said reduceddiameter, a circumferential rabbet about said body, a gage ring havingabout its circumference at least one row of hardened meta inserts, andmeans securing said gage ring on said reduced diameter of said body andin said circumferential rabbet.